Momentary retaining translation means for multiple switches



United States Patent Kenneth C. Gaspar Canoga Park, California 716,626

March 27, 1968 Dec. 1, 1970 RCA Corporation a corporation of Delaware lnventor Appl. No. Filed Patented Assignee MOMENTARY RETAINING TRANSLATION MEANS FOR MULTIPLE SWITCHES 4 Claims, 1 Drawing Fig.

U.S. Cl 200/5, 200/18, 200/153; 340/322 Int. Cl H0lh 9/26 Field of Search 0/5, 18,

[56] References Cited UNITED STATES PATENTS 2,973,846 3/1961 Burstein 192/40X 2,998,873 9/1961 Burstein l92/22X 3,227,823 1/1966 Acker ZOO/18X 2,381,978 8/1945 Mathes.... 200/5(E)UX 2,438,496 3/1948 Deakin 200/5(E)UX 2,831,075 4/1958 Dumke et a1. 200/5(E)UX 3,271,530 9/1966 Wirsching 200/5(C)UX 3,271,757 9/1966 Wales, Jr 200/5(B)UX Primary Examiner- Robert K. Schaefer Assistant Examiner-J. R. Scott An0rney-H. Christoffersen ABSTRACT: A keyboard having a system for translating key movements into coded electrical signals by selective operation of a plurality of electrical switches and incorporating a clamping apparatus for the switch actuating devices to momentarily retain a switch actuated state of the devices to insure an accurate switch readout.

PATENTEI] DEB] I970 I N VEIV TOR fa/w? 6 511m B Y J NW R R Q wk .V I I! w a s kw gm Q QM I 4 W \N NM R M Q 47' TWINE) I MOMENTARY RETAINING TRANSLATION MEANS FOR MULTIPLE SWITCHES BACKGROUND OF THE INVENTION The use of keyboards as data entry devices for digital computer systems has created the problem of accurately translating the operator induced movements of the keys in the keyboard into coded electrical signals suitable for use in the computer system. One data entry keyboard for such use has a mechanical coding system wherein key movements are translated to corresponding coded actuation ofa group of electrical switches. This type of apparatus has inherent readout problems caused by the fact that the switch closure times are not accurately synchronized and the switch closure interval is not controlled. Accordingly, it is desirable to have a keyboard data entry device wherein the translation of key movements to electrical signals is controlled by predetermined operational characteristics to produce an accurate readout of the translated data.

BRIEF SUMMARY OF THE INVENTION Apparatus embodying the present invention includes a control apparatus for a keyboard device which converts a mechanical key movement into a corresponding coded actuation of a plurality of electrical switches by means ofa plurality of selectively movable switch-actuating rods. The rods are all momentarily clamped after they have been actuated to a switch actuating position to insure an accurate readout of the actuated switches.

DESCRIPTION OF THE DRAWINGS The single figure drawing is a pictorial illustration of an embodiment of the present invention used in a keyboard apparatus.

DETAILED DESCRIPTION A keyboard having a plurality of keys 12 is arranged to convert a mechanical key actuation by an operator into a corresponding selective movement ofa plurality of rods, shown as rods 13, I4, and 16. For example, an actuation of one of the keys 12 would result in a movement of rods 13 and 14 while a movement of another one of the keys 12 would move rods 13, 14 and 16. Such keyboards are well known in the art, and the details of their internal construction and operation does not form a part of the present invention. The rods 13 to 16 are arranged to move in the direction shown by the arrow when actuated by the keys ofthe keyboard 10.

A fixed support 19 is positioned under the rods 13 to 16 and is used to guide the rods 13 to 16. This support may be advantageously made of a low friction material, e.g., nylon. The rods 13 to 16 extend past the support 19 to a group of switches 21, 22, 23 and 24 mounted on a common support 25. Each of the rods 13 to 16 is operatively associated with a respective one of the switches 21 to 24, e.g., rod 13 is associated with switch 21. The ends of the rods 13 to 16 are spaced from the associated'ones ofthe switches 21 to 24 by a distance which is equal to the keyboard induced movement ofthe rods 13 to 16 minus the distance required to actuate an associated one of the switches 21 to 24. Thus, the movement ofa rod by a key 12 is sufficient to actuate the corresponding one of the switches 21 to 24. The switches 21 to 24 are connected by respective electrical lines 21a, 22a, 23a and 24a (not shown) to associated equipment, e.g., a digital computer.

A clamping bar 30 is slideably supported between a pair of slotted guide posts 31 and 32 with the bottom of the bar 30 being located above and normally spaced from the rods 13 to 16 while, also being parallel to the top edge of the plate 19 supporting the rods 13 to ]6. ln order to assure the proper positioning of the bar 30 and the plate 19, they may both be located in the slots of the guide posts 31 and 32. A centrally located opening 35 is provided in the clamp bar 30. A lever arm 37 is pivoted on a fixed pivot 39 located intermediate the ends of the lever 37. One end 37a of the lever arm 37 is fitted into the opening 35 in the clamp bar 30 while the other end 37b of the lever arm is urged against a cam member 40 by a spring 41. The cam 40 is selectively rotated by a motor 42. A motor drive circuit 43 is momentarily energized by the keyboard 10 upon an actuation of any of the keys 12, e.g., a common switch is operatively connected to all of the keys 12. The motor drive circuit 43 produces an energizing drive pulse for a clutch 44 which momentarily connects the continuously rotating motor 42 to the cam 40. Such clutch mechanisms are well known in the art and may be of the type shown in U. S. Pat. Nos. 2,973,846 and 2,998,873, both by Albert Burstein. Alternatively, other devices could be used to produce the drive for the cam 40, e.g., the motor 42 could be a stepping motor directly to the cam 40 and operated by a signal having a predetermined pulse width.

In operation, the illustrated embodiment of the present invention produces a coded actuation of the switches 21 to 24 by the movement of selected ones of the rods 13 to 16 in response to the operation of one of the keys 12 on the keyboard 10. Concurrently, the motor drive 43 is energized to produce a drive signal for the clutch 44 to connect the cam 40 to the continuously running motor 42. This drive signal is a pulse-type momentary signal which is effective to activate the clutch 44 to produce a rotation of the cam 40.

The illustrated cam 40 is provided with a pair of opposite high cam surfaces connected by intermediate low cam surfaces. In the unactuated position. the cam 40 presents a low surface to the cam end 37b of the lever 37. The normal position ofthe lever 37 on the pivot 39, thus, is determined by one ofthe low surfaces ofthe cam 40. This position ofthe lever 37 raises the clamp bar 30 by means of the end 37a of the lever 37 to a position clear of the rods 13 to 16. On the other hand, when a high surface ofthe cam 37 is presented to the cam end 37b, the lever 37 is pivoted on the pivot 39 to drive the bar 30 against the rods 13 to 16. Since the high and low surfaces of the cam 40 are alternately located on the cam 40, a 180 rotation of the cam 40 is effective to cycle the cam surface adjacent to the lever end 37b from a low surface to a high surface and, then, to a low surface. During this cycle, the lever 37 is pivoted on the pivot 39, the clamp bar 30 is pressed against the rods 13 to 16, and, subsequently, the clamp bar 30 is restored to a spaced position with respect to the rods 13 to 16. Thus, following an actuation ofone of the keys 12, the rods 13 to 16 are selectively moved to produce a coded operation of the switches 21 to 24.

After a short delay determined by the time constant of the motor drive 43 and the inertia ofthe motor 42 and cam 40. the cam 40 is driven through 180 successively clamp and unclamp the rods 13 to 16 while they are in a switch operating position. This delay is selected to ensure that all the rods are in a switch operating position, while the cam cycle is selected to have an elapsed time which does not interfere with the normal operation of the keyboard 10. On the other hand, the rods 13 to 16 are momentarily retained in a switch actuated position for a predetermined time, whereby the coded switch pattern can be accurately determined and the possibility of variations in the operating time of the rods 13 to 16 affecting this switch readout is eliminated.

lclaim:

l. A combination comprising a keyboard having keys, means for translating a movement of said keys in said keyboard to representative signals and means for momentarily retaining said last-mentioned means in a translating state following a key movement and for automatically releasing said means for translating before a succeeding key movement, said means for momentarily retaining including a clamp means for clamping said means for translating to retain said translating state and means responsive to the actuation ofany ofsaid keys for operating said clamp means, said means responsive to the actuation of any of said keys including a delay means for delaying an actuating signal for said clamp means to produce an energization of said clamp means when said means for translating is in a translating state.

2. A combination as set forth in claim 1 wherein said means for translating includes a plurality of rods selectively actuated by said keys in a coded pattern and a plurality of electrical switches operatively associated with respective ones of said rods to produce a coded electrical signal pattern corresponding to a said selective actuation of said rods, said clamp means being operativeto clamp said rods to retain an actuated state.

3. A combination as set forth in Claim 2 wherein said clamp means includes a guide means supporting said rods, a clamp bar normally spaced from said rods and positioned from said 

